Response and pressure build-up time for air brake systems must meet guidelines, such as established by various governmental agencies, for example. These requirements are met by installing relay valves in the brake systems. It has been found, however, that the times for response and pressure build-up could still be reduced. By installing load-controlled brake pressure regulators, brake pressure control is obtained which is dependent upon the load weight of the vehicle and with which the respective brake forces on the axles for effecting deceleration are adjusted relative to one another in such a manner that the maximum frictional resistance at all the wheels is approximately the same. The guidelines above referred to regarding the observance of adhesion curves which represent the relationship of deceleration to coefficient of adhesion, require the installation of automatic load-controlled brake pressure regulators in commercial vehicles and trailors.
The installation of such valve arrangements within a brake system, as above described, requires more space for installation and a relatively high cost for construction of the individual valve devices themselves, as well as the pipes for connecting them. The use of load-controlled brake pressure regulators and relay valves, which are connected therewith and which are controlled by the regulated brake pressure, are presently known. In such an arrangement, the relay valve is connected with a fluid pressure source, such as a reservoir, for example, and, in well known manner, causes fluid pressure to be supplied from the reservoir to the brake cylinders, as a function of the regulated brake pressure supplied. A further disadvantage in addition to those previously mentioned, is the fact that a relatively long time interval lapses from the moment the brake valve is actuated until the full brake pressure effect in the brake cylinders is attained (response time plus pressure build-up time).